1. Technical Field
This invention relates generally to internal combustion engines, and more particularly to vapor vent systems for outboard marine fuel injected engines vent systems have a snap assembly decoupled float vapor vent.
2. Related Art
It is a long recognized problem in the internal combustion engine art that heat build-up of an engine can adversely effect the fuel supply system of the engine thereby causing the fuel to vaporize before it is introduced into the engine's combustion chambers. This condition, commonly referred to as vapor lock, can not only have a damaging effect upon engine components but can result in poor engine performance, overheating and interrupted engine operation. Fuel vapor is particularly disadvantageous in fuel injected engines. Typically, in fuel injection engines, fuel is introduced into a fuel rail by a high pressure fuel pump before it is injected into the combustion chambers by the fuel injectors. The fuel rail is typically heated to relatively high temperatures due to engine combustion heat, and the heated fuel is returned back to the fuel system during periods of low engine use such as idling and start and stop operation.
Usually, the heated fuel from the fuel rail is returned to a vapor separator where any fuel vapor created by the heated fuel is condensed back to liquid fuel before the fuel is reintroduced into the high pressure pump and fuel rail. Such vapor separators heretofore known to the art have used some form of coolant passing through the separator to cool the heated fuel and condense any fuel vapor back into liquid fuel. In most outboard Marine applications, for example, the liquid coolant is supplied from the operating environment and lake or sea water is circulated through the engine for cooling. However, because such water may have contaminants such as weeds, flotsam, or small biological life forms floating in the water, there is a risk that the engine cooling system and vapor separator may become clogged with debris and contaminants. An additional disadvantage of prior art vapor separators is that they can be expensive to manufacturer because of the intricacy of the component parts and long assembly time. Thus, it would be a desirable advanced in the art to have a vapor separator which is relatively easy to fabricate and which reduces the potentiality for clogging with contaminants.
One way to avoid fuel vapor from being directed to the fuel injectors is described in U.S. Pat. No. 6,857,419. Fuel vapor that is not condensed during cooling of the engine escapes from the chamber through a float needle valve at the top of the chamber. A pressure relief valve is provided at the top of the chamber to allow the vapor to escape when a predetermined internal pressure is reached, as depicted in FIG. 1. FIG. 1 shows a top wall assembly of a vapor separator in accordance with the prior art. A vapor passage 246 which terminates at vapor outlet 248 is formed through top wall assembly 232. Positioned at the lower end of vapor passageway 246 is needle valve assembly 250 which comprises a needle valve plunger 252 and a needle valve seat 254. A float assembly 256 is mounted to needle valve assembly 250 and comprises a support arm 258 and a float 260 attached to one end of float arm 262. The other end of float arm 262 is pivotally mounted to support arm 258 by a pivot pin 264 so that float 260 can pivot up and down. Needle valve plunger 252 is mounted on float arm 262 so that when float 260 is pivoted upwardly needle valve plunger seats against needle valve seat 254 sealing the needle valve. However, when float 260 pivots downwardly, needle valve plunger disengages needle valve seat 254 opening the valve and allowing vapor and air in the chamber to pass through the needle valve into vapor passageway 246 and out vapor outlet 248.
Referring to FIG. 2, a closed biased vent valve is used to separate vapor and/or air from a liquid in an enclosed chamber. The closed biased vent valve 210 is operated by a float 272 which is installed in the fuel chamber 270 of the fuel vapor separator 230 and has an upwardly extending float arm 268 that pivots the lever arm 214 against the force of a spring. Specifically, the upwardly float arm 268 and the lever arm 214 have hooks 269 and 219, respectively. When the fuel vapor separator 230 is filled with fuel to a designated fill level with a consequent upward movement of the float 272, the hook 269 and the hook 219 decouple from one another. As a result, the closed biased vent valve 10 remains in its closed position. Conversely, when the fuel vapor separator 230 is empty, or the fluid level in the enclosed fuel chamber 270 is depleted due to the accumulation of vaporized fuel in the enclosed fuel chamber 270, the float 272 drops below the designated level in the enclosed fuel chamber 270. During this movement, the hook 269 and the hook 219 couple with one another such that the valve 210 is placed in its open position to release vaporized fuel from the fuel vapor separator 230.